import launch
import launch_ros
from ament_index_python.packages import get_package_share_directory

def generate_launch_description():

    urdf_tutorial_path = get_package_share_directory('robot_description')
    default_model_path = urdf_tutorial_path + '/urdf/robot.urdf'
    default_rviz_config_path = urdf_tutorial_path + '/config/rviz/display_model.rviz'

    action_declare_arg_mode_path = launch.actions.DeclareLaunchArgument(
        name='model',default_value=str(default_model_path),
        description='URDF 的绝对路径'
    )

    robot_description = launch_ros.parameter_descriptions.ParameterValue(
        launch.substitutions.Command(
            ['cat ', launch.substitutions.LaunchConfiguration('model')]
        ),
        value_type=str
    )
    
    robot_state_publisher_node = launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description':robot_description}]
    )

    joint_state_publisher_node = launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher',
    )

    rviz_node = launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        arguments=['-d',default_rviz_config_path]
    )

    return launch.LaunchDescription([
        action_declare_arg_mode_path,
        joint_state_publisher_node,
        robot_state_publisher_node,
        rviz_node
    ])
